[Milsurplus] [ARC5] Opinions on ARR-7

[J. Forster]

It seems the set was designed as an ELINT receiver for detecting and
analyzing enemy HF RADARS. As such, sensivity is not really at issue. Even
a receiver with no RF stages can easily see a RADAR looong before it can
possibly see you.

-John

=================


> I did make one small
>> modification to it - jumpered plate and grid of the anti-radiation
>> isolation stage with a small mica capacitor soldered to a couple of tube
>> pins inserted into the tube socket. The original design simply added a
>> bunch of noise to the receiver without any useful purpose.  I made the
>> same change to the ARR-5 input stage.  Pairing with an AN/APA-10
>> panadapter and an APA-6 or -11 pulse analyzer is an interesting thing to
>> do if you have the space and power.  I normally use it with an
>> interphone amplifier to get the power for a speaker - the LS-184/AIC-10
>> - but any outboard amp can of course be used.
>
> The Navy was paranoid about oscillator leakage being picked up by the
> enemy
> and had many receivers modified with an additional RF stage, tuned or
> untuned. From what Ive read on the subject it is highly doubtful that the
> enemy had sufficient technology during WW2 to detect it unless they were
> well under a half mile away.
>
> Perhaps, also, the ARR-7 was deliberately desensitized to limit
> interference
> from distant signals as well as minimize images due to only a single tuned
> RF stage that plagues many receivers on the higher frequencies when using
> only a 455kc or similar IF.
>
>